1. Field of the Invention
The present invention relates to an alternating-current plasma display panel (ACPDP), and more particularly, to a three-electrode surface-discharge ACPDP.
2. Description of the Related Art
FIG. 1 shows a structure of a general three-electrode surface-discharge ACPDP, FIG. 2 shows an electrode line pattern of the PDP shown in FIG. 1, and FIG. 3 shows an example of a pixel of the PDP shown in FIG. 1. Referring to the drawings, in a general three-electrode surface-discharge ACPDP 1, address electrode lines A1, A2, Am, dielectric layers 11 and 15, scan electrode lines Y1, Y2, Yn, common electrode lines X1, X2, Xn, phosphors 16, partition walls 17 and a MgO protective film 12 are located between front and rear glass substrates 10 and 13.
The address electrode lines A1, A2, Am, are arranged over the front surface of the rear glass substrate 13 in a predetermined pattern. The lower dielectric layer 15 covers the entire front surface of the address electrode lines A1, A2, Am. The partition walls 17 are located on the front surface of the lower dielectric layer 15 parallel to the address electrode lines A1, A2, Am. The partition walls 17 partition discharge areas of the respective pixels and prevent cross talk among the respective pixels. The phosphors 16 are coated between the partition walls 17.
The common electrode lines X1, X2, Xn and the scan electrode lines Y1, Y2, Yn are arranged on the rear surface of the front glass substrate 10 orthogonal to the address electrode lines A1, A2, Am, in a predetermined pattern. The respective intersections define corresponding pixels. The common electrode lines X1, X2, Xn and the scan electrode lines Y1, Y2, Yn each comprise indium tin oxide (ITO) electrode lines Xna and Yna, and a metal bus electrode lines Xnb and Ynb, as shown in FIG. 3. The upper dielectric layer 11 is entirely coats the rear surface of the common electrode lines X1, X2, Xn and the scan electrode lines Y1, Y2, Yn. The MgO protective film 12 for protecting the panel 1 against strong electrical fields entirely coats over the rear surface of the dielectric layer 11. A gas for forming plasma is hermetically sealed in a discharge space.
The driving method generally adopted for the PDP described above is an address/display separation driving method in which a reset step, an address step and a sustain discharge step are sequentially performed in a unit sub-field. In the reset step, wall charges remaining from the previous sub-field are erased. In the address step, the wall charges are formed in a selected pixel area. Also, in the sustain discharge step, light is produced at the pixel at which the wall charges are produced in the address step. In other words, if alternating pulses of a relatively high voltage are applied between the common electrode lines X1, X2, Xn and the scan electrode lines Y1, Y2, Yn, a surface discharge occurs at the pixel at which the wall charges are located. Here a plasma is formed at the gas layer of the discharge space 14 and the phosphors 16 are excited by ultraviolet light and thus emit light.
In the above-described plasma display panel 1, conventionally, the common electrode lines X1, X2, Xn and the scan electrode lines Y1, Y2, Yn are all a rectangular solid.
FIG. 4 shows the common electrode lines X1, X2, Xn and the scan electrode lines Y1, Y2, Yn of the conventional three-electrode surface-discharge alternating-current plasma display panel. In FIG. 4, reference numeral 10 denotes a front-surface glass substrate. Referring to FIG. 4, the respective common ITO electrode lines X1a, X2a, Xna have the same cross-section area, irrespective of their lengthwise positions. Accordingly, the cross-sectional resistance values of the common ITO electrode lines X1a, X2a, Xna are the same at any lengthwise position. The same structural and electrical characteristics are also applied to common bus electrode lines X1b and Ynb, scan ITO electrode lines Y1a, Y2a, Yna and scan bus electrode lines Y1b, Y2b, Ynb.
In to the aforementioned conventional electrode line structure, the farther from the input terminals of driving signals, the lower the driving voltages become, because of a voltage drop due to line resistance. Thus, since the amounts of discharged current flowing in the common electrode lines X1, X2, Xn and the scan electrode lines Y1, Y2, Yn are different according to their lengthwise positions, the luminance of the display is not uniform. This phenomenon can be somewhat improved by constructing the electrode line structure such that the positions CX of input terminals to which driving signals corresponding to the common electrode lines X1, X2, Xn are opposite to the positions CY of input terminals to which driving signals corresponding to the scan electrode lines Y1, Y2, Yn are applied. In other words, the luminance of the display at the respective positions with respect to average time can be made uniform utilizing the characteristic of alternating-current driving.
However, the amounts of discharged current are relatively small at the central positions CM . . . , the common electrode lines X1, X2, Xn and the scan electrode lines Y1, Y2, Yn, thereby lowering luminance.
To solve the above problem, it is an objective of the present invention to provide an alternating-current plasma display panel (ACPDP) which can improve a picture quality by providing uniform luminance of the display throughout the screen.
Accordingly, to achieve the above objective, there is provided an alternating-current plasma display panel having common electrode lines, scan electrode lines and address electrode lines arranged between first and second substrates opposite to and spaced apart from each other, the common electrode lines being arranged parallel to the scan electrode lines, the address electrode lines being arranged orthogonally to the common electrode lines and the scan electrode lines, to define corresponding pixels at the respective intersections, wherein the positions of input terminals to which driving signals corresponding to the common electrode lines are opposite to the positions of input terminals to which driving signals corresponding to the scan electrode lines, and the top plane areas of the respective common bus electrode lines and the respective scan bus electrode lines are gradually increased toward the corresponding input terminals.
In the ACPDP according to the present invention, the cross-sectional resistance values of the respective common electrode lines and the respective scan electrode lines are decreased toward the corresponding input terminals. In other words, when a voltage is applied to the corresponding input terminals, the amount of current flowing between the input terminals and the central positions is maximized. Accordingly, the amounts of discharged current and the luminance at the central positions of the common electrode lines and the scan electrode lines can be relatively increased, thereby improving the picture quality because of the uniform luminance of the display for the overall screen.